New Research Analyzes Countries at Greatest Risk from Climate Change Impacts

The first global study to identify populations at greatest risk from rising sea levels and more intense cyclones as a result of climate change will be published in the peer-reviewed journal Environment and Urbanization. The study was conducted by scientists at the Center for International Earth Science Information Network and the International Institute for Environment and Development.

By overlaying layers of geographic data, the researchers calculated the population and land area of each country, in areas of low elevation coastal zones, and then summarized the data by country, region, and country income category.

"Of the more than 180 countries with population in the low-elevation coastal zone, 130 of them — about 70% — have their largest urban area extending into that zone," says Bridget Anderson, research associate at Columbia University's Center for International Earth Science Information Network. "Furthermore, the world's large cities —those with more than 5 million residents — have, on average, one-fifth of their population and one-sixth of their land area within this coastal zone." The researchers argue that such vulnerabilities should be considered in preventing extensive damage to lives and livelihoods in the years to come.

Key findings of the study, which include an analysis of 224 countries, include:

Nearly two-thirds of urban settlements with more than 5 million inhabitants are at least partially in the 0 to 10 meter low elevation coastal zones (LECZ).

On average, 14 percent of people in the least developed countries live in the zone (compared to 10 percent in OECD countries).

21 percent of the urban populations of least developed nations are in the zone (11 percent in OECD countries). About 75% of people in the zone are in Asia.

21 nations have more than half of their population in the zone (16 are small island states).

247 million people in low-income countries live in the low-elevation coastal zones.

The research shows that 634 million people — one tenth of the global population — live in coastal areas that lie within just ten meters above sea level, and are therefore, at great risk of sea-related impacts of climate change. Although the low elevation coastal zone accounts for only about 2 percent of the world’s land area, about 10 percent of the world’s population and 13 percent of the world’s urban population live in these vulnerable zones.

"Urban development in the coastal zone brings multiple risks," says Gordon McGranahan, Director of the Human Settlements Group at the International Institute for Environment and Development. "It exposes people to seaward hazards such as storms, flooding and cyclones, and it can damage sensitive ecosystems including those such as mangrove forests that protect the coastline."

The study reveals that human settlements in the LECZ are likely to be especially vulnerable in lower-income countries with limited resources; all but two of the countries with the largest shares of their population in these areas (excluding the very small countries) are of low or lower-middle income. In terms of the regional distribution, Asia stands out in particular, as it contains about three-quarters of the population in the zone and two-thirds of the urban population.

Last month the Intergovernmental Panel on Climate Change's (IPCC) latest report warned that sea levels could rise by tens of centimeters this century, making coastal populations more vulnerable to flooding and storm surges. It also predicted more intense tropical cyclones (typhoons and hurricanes).

"The IPCC is aware that there are high population densities in coastal areas, but it has not yet recognized the links to urbanization, and the implications for adaptation to climate change," says co-author Deborah Balk, acting associate director of the Institute for Demographic Research at the City University of New York and adjunct research scientist at Center for International Earth Science Information Network.

Effective adaptation will require a combination of effective and enforceable regulations and economic incentives to redirect new settlement to better-protected locations and to promote investments in appropriate infrastructure, all of which require political will as well as financial and human capital.

The study will be published on April 14, along with papers that focus on specific cities, including Cotonou (Benin), Dhaka (Bangladesh), Mumbai (India) and Shanghai (China). The ten countries with the largest number of people living within ten meters of the average sea level are (in descending order): China, India, Bangladesh, Vietnam, Indonesia, Japan, Egypt, United States, Thailand, and the Philippines.

The ten countries with the largest share of their population living within ten meters of the average sea level are: Bahamas (88%); Suriname (76%); Netherlands (74%); Vietnam (55%); Guyana (55%); Bangladesh (46%); Djibouti (41%); Belize (40%); Egypt (38%); and the Gambia (38%).

About The Center for International Earth Science Information Network (CIESIN)
The Center for International Earth Science Information Network (CIESIN) is a center within the Earth Institute at Columbia University. CIESIN works at the intersection of the social, natural, and information sciences, and specializes in on-line data and information management, spatial data integration and training, and interdisciplinary research related to human interactions in the environment.